Evolutionary ecology of Great Lakes alewives: An analysis of phenotypic patterns and rates of change

Session: Invasive Species (4)

Shelby Smith , Western Michigan University , [email protected]
Eric Palkovacs, University of California Santa Cruz: Ecology & Evolutionary Biology Department, Institute of Marine Sciences and IMS-National Marine Fisheries Services at Long Marine Lab, [email protected]
Brian Weidel, U.S. Geological Survey, Great Lakes Science Center, [email protected]
Devin Bloom, Western Michigan University: Department of Biological Sciences and Institute of the Environment and Sustainability , [email protected]

Abstract

Invasive species impart devastating environmental and economic tolls on aquatic ecosystems, particularly in the Great Lakes. However, invasive species also pose exciting opportunities for studying rates and patterns of evolutionary change in a novel environment. Although alewives (Alosa pseudoharengus) are anadromous fishes native to the East Coast of North America, multiple native East Coast populations have become landlocked in small inland lakes within the past several thousand years.  Landlocked alewives have rapidly evolved smaller gill raker spacing and gape width as the result of a shift in zooplankton prey size. More recently, alewives have been introduced in the Great Lakes via shipping canals or stocking. In this study, we compared phenotypic traits of alewives in the Great Lakes, a dynamic ecosystem vastly different than small inland lakes. Our results show that gill raker spacing is consistent with anadromous populations, while gape width, body shape and size is convergent with East Coast landlocked populations. We suggest that the cessation of migration can result in rapid convergent evolution in traits associated with motility and trophic niche, but that contingency also plays a role, and the complex and dynamic ecosystem of Great Lakes results in novel trait combinations.